Thread cutter



June l5, 1965 E. FREEMAN ETAL I 3,188,992

n THREAD CUTTER Filed oct. 29, 1962 v 2 sheets-sheet 1 ya /ff f6 4Z June l5, 1965 E. FREEMAN ETAL 3,188,992

THREAD CUTTER Filed Oct. 29, 1962 2 Sheets-Sheet 2 United States Patent O York ` Filed Oct. 29, 1962, Ser. No. 233,604

4 Claims. (Cl. 112-252) The present invention relates generally to improvements in sewing machines, and it relates in particular to an improved threadV cutting mechanism employed in combination with a sewing machine.

yIn machine sewing operations, particularly in the commercial mass production of garments or the like, it has Ibeen the conventional practice to successively sew successivesimilar panels or work pieces. These successive panels, as they emerge from the sewing machine head, carry trailing chains of stitches which are either cut with the emergence of each work piece or are permitted to be joined to the next successive work pieces and are subsequently cut prior to t-he next operation on the particular work piece. In either case, the work piece separating procedure is inconvenient and time-consuming and thereby increases the cost of the end product, Various types of sewing machine thread cutters, both of the automatic and hand operated type, have been employed and proposed but these possess numerous drawbacks and disadvantages. The hand operated thread cuttersv otter little advantage over the manual cutting of the thread, whereas the automatic thread cutters are complex mechanisms whose general operation leave much to be desired. In addition to their other drawbacks, the automatic thread cutters heretofore available frequently left long thread tails on the work pieces which are highly undesirable and are generally to be avoided.

r It is, therefore, a principal object of the present invento'provide an improved sewing machine.

. Another object of the present invention is to provide animproved automatic thread cutter for sewing machines. f Still another object of the present invention is to provide, in a sewing machine, an improved mechanism for cutting the threads between successive work pieces in a neat and trim manner.

A further object of the present invention is to provide a thread cutting mechanism of the above nature characterized by its simplicity, ruggedness, reliability and verfsatility.

The above and other objects of the present invention will become apparent from a reading of the following description, taken in conjunction with the accompanying drawings, wherein FIGURE l is a top plan fragmentary View of a preferred embodiment of the present invention;

FIGURE 2 is an enlarged sectional view taken along line Z-Q of FIGURE l;

FIGURE 3 is an enlarged sectional view taken along line 3-'3 of FIGURE l, the thread cutting ele-ment being illustrated in its advanced position;

FIGURE 4 is a view similar to FIGURE 3, the thread cutting element being illustrated in its retracted position;

lFIGURE 5 is a sectional view taken along line 5--5 of FIGURE 3;

FIGURE 6 is la sectional view taken along line 6--6 of FIGUREl 4; and

FIGURE 7 is a diagrammatic view illustrating the stroke of the cutting element relative to the successive work pieces.

In a sense, the present invention contemplates the provision, in combination with a sewing machine including means for advancing a work piece along a predetermined path past a sewing needle, of a thread cutting member movable between an advanced and a retracted position across said path forward of said needle, and means responsive to the presence and absence of said Work piece at a predetermined point uriging said cutting member alternatively respectively to said advanced and retracted positions.

According to a preferred form of the present mechanism, the thread cutting member is dened by a hot wire electrical resistance element the ends of which are connected to corresponding of a pair of parallel metal bars separated by a sandwiched sheet of insulating material and joined to form an assembled arm which is pivotally supported below the work piece path. The bars are connected to a source of low voltage current. A sensing element is defined by a pivoted arm swingable in a vertical plane in the vicinity of the sewing machine foot piece, the foot piece carrying a laterally spaced arm which restricts the vertical movement of the work piece in the sensing area, the sensing element registering with a space between the foot piece and the laterally spaced arm. The pivoted sensing arm engages the cutting member supporting arm to retract the latter when the sensing arm is depressed and the cutting member arm is gravity urged to its advanced position normally to urge the sensing arm to its raised advanced position. A suction pipe is provided having an opening forward of and directed toward the retracted cutting member.

Referring now to the drawing and particularly to FIG- URES 1 to 7 thereof, which illustrate a preferred embodiment of the present invention, reference numeral 10 generally designates a reciprocating needle bar of a conventional sewing machine which releasably engages a sewing needle 1.1 in the usual manner. The sewing machine includes an L-shaped throat plate 12 secured to and extending laterally from the machine base plate 13, and provided with an inner transverse edge 14 conlfronting and spaced from the end edge of base plate 13 to define therewith a longitudinally extending recess 16. Formed in throat plate 12 are a pair of laterally spaced slots having the usual reciprocating feed dogs 17 registering therewith and a needle receiving opening.

A foot piece 18, having a cur-ved front upwardly curved end 19, is located in vertical alignment with throat |plate 12 and is supported by a bracket arm 19 at its rear end. Bracket arm 19 and foot piece 18 are selectively movable between a raised position and a depressed position in engagement with feed dogs 17 in the usual manner, and the foot piece 1S has a needle registering opening formed therein. In order to restrict the vertical movement of lthe Work piece in the sensing area, there is provided a guide arm 2t) extend-ing along the length of the opening 16 and substantially coplanar with the underface of foot piece 18. Guide arm 20 registers with opening 16 and is laterally spaced from edge 14 of the `throat plate to delineate therebetween a sensing area.

A bracket assembly 21 is positioned under base plate 13 and includes an upper transversely extending plate 22 afhxed to the underface of base plate 13 by screws 23. Depending from plate 22 intermediate the ends thereof is a iirst bracket plate 24, and depending from the leading end of plate 22 is a second bracket plate 26 adjacent to the leading end of throat plate 12. A pivot screw 27 engages a tapped bore in bracket plate 26 and is rotatably engaged by a block 28 which is sandwiched between the head of screw 27 and a spacer 29 engaging screw 27.

A cutter lever assembly 30 is mounted on block 28, rockable therewith, and is formed of a pair of electrically conducting upper and lower metal bars 32 and 33 respectively, separated by an intermediate substantially coextensive band 34 of suitable insulating material. Bands 32,

33 and 34 are mutually secured byscrews'36 engaged by ,I

insulating sleeves 37 and opposite insulating washers to separate electrically the bars 32 and 33. Y grounded Athrough block 27 and by way of a flexible Ylead 38, and bar 32 isconnected by a flexible lead 39'to `a terminal of a high current lowvoltage source, the other terminal of which is grounded. The voltage source'may be the secondary of a step-downtransformer, the primary of which is connected to the standard A.C. powerline.

Mounted at the4 end of lever 30 is a cutting element-40 Bar sais it is released for upward movement, permitting lever assembly 30 and sensing member 49 to swing to their raised positions.. The rising cutting member 40- seversthe chain L adjacent the trailing edge-of work piece XV and where the thread is thermoplastic, it fuses and seals .the chain ends. The tail L, which isjattached to the next successive l VworkV piece Wis drawnv toward and ninto the suction conformed of a U-shaped rmetal rodhaving a co'ns'tricted A. looped end section 41, the opposite legs 42 of the cutting Y element 40l being rrnly connected tothe ends of the conductor bars 32 and 33 respectivelyV (see FIGURE 3 )L fThe resistance Vof element 40 is greater than that of bars 32 and.

33 so that the resistance-heating is primarily confined to element 40 which reaches a temperature which will readily burn and sever the conventional'sewing threads and duit 51.. As the leading edgeof the next successivework piece W travels across Vspacel, it depresses sensing member 49 which in turn depresses lever assembly l30 and Vcutting member740 toseverthe stitch tail L'immediately forward of the .work piece leadingedge 'and the severed tail L is completely drawn into the suction conduit 51.

While there has been described and illustrated a preferred embodiment ofthe present invention, it isfapparent that numerous alterationsL omissions and additions may ybe made 'without*departingV from the spirit thereof.

What isv claimed and desired tobe secured by Letters Patent'is: 7, Y

1. In combination with a sewing machine including a sewing Yneedle and means :for advancing a Work piece al'ong'a predetermined path past said sewing needle, a

. pivotally mounted arm swingable between a raised and Vting element 'mounted on and extending beyondsaid arm stroke of the cutting element 40eltects the severing of any Y thread, such as a chain of stitching, which is ydelivered by the sewing machines and carried forwardly.L The cutting element 40 is limited in movementr to its'advanced or raised position, asillustrated in FIGURE 3, and to its depressed or retracted position, as illustrated in FIGURE 4,

by Van angulated member having one arm 43 a'iiixed tothev a depressed position and means normally urging said arm to said raised position, anelectrically heated hot wire cutand swingable with said arm between a raised'and a depressed position across said work piece path forward of underface of pivoted block 28 vand anotherarm 44 swingc able with the lever assembly-30 into Vengagement'with spaced opposing abutments 46 and 47 respectively.A

Pivoted to bracket plate 24 by means of Ya pin 4Sisa `sensing member-defining fork 49 having anupper leg 50 registering withelongated opening 16; The 'lower edge of e leg 50 engages the upper surface of bar 32 adjacentthef cutting element and the upper edge of the 1eg50 is upwardly convex. Fork member 50, cutter assemblyt) and the path of the work pieceasV advanced by the sewing said needle, and a pivotally mounted actuating member including a cam surface along its upper edge rdisposed along the path of said work piece and'movable with said actuatingimember between a raised and a depressed position, saidactuating member furtherinCIudingan undersurface registering with the upper surface'of said arm whereby said Vactuating lmember is normally held in its raised lposition by said arm and saidrurging means and movable to said depressed position whensaid cam surface is depressed byrengag'ementwith a workpiece passing thereover to thereby effect a movement of said arm and saidfeutting element between said raised and depressed positions in'response to `the respective raising andrdepression of said actuatingmember to thereby cutthreads posimachine are so related that inthe absence of'a work piece j over opening 16 the sensing member 49 is swung clock? wise to its raised position,` as illustrated in FIGURE.5,by

the swinging of the lever assembly 30 to its raisedr position, f and the movement rof a work piece into registry with opening 16 swings sensing member 49 to its depressed position as seenin FIGURE 6, leg Vin turn bearing upon and o depressing the leverlassembly 30. ;4 v A suction conduit 51,- which is connected to ay source of negative pressure, is positioned beneath and along-the i means located base plate 13 and terminates in a rearwardly directed intake opening 52 confronting the plane offmovement of the cutting element 40 immediately below vthe stitching line. The sewing machine described abovefisemployed in .the

usual'manner. Prior to the sewing operation, the current circuit to the cutting member 40 is closed to bring it yto operating temperature. Cutting member 40, leverassembly 30 and the sensing member t9vare initially in their raised,

positions. A work piece VVW is fed tothe sewingvmachine and thersewing machine is actuated." The workpiece W is advanced byl feed-dogsV 17 and stitching applied there;l to. The advancing work piece W travels across openingY 16Y to engage and depress Vsensing member 49v which in Vturn depresses lever assembly 30 and cutting member 40 below the level of the` workV piece. When the endof .the

work piece W passes the sewing needle, it carries with it'a trailingtail or chain of thread orstitches,'and asthe trailing edge of thework piece W passes the sensing member 49 vf 'counterbalancing saidarm normally toV urge said cutting Y'element toward'its raised position. Y

" 4. The. combination of claim 1 including a suction adjacent to said path lof said cutting element. e Y e y References Cited bythe Examiner l UNITED STATES PATENTS [2,082,738 6/37 vesconte. ,Y Y

V2,148,377 i 2/39 Lutz 4 112-252 2,151,438 3/39 Pierce 112--252 2,398,473 Y 4/46 Stahl et al. 112-252 X f 2,989,935 6/61 VButler i12-252 j V3,008,437 n 1,1/61 Herr 112--252 'JORDAN FRANKLIN; Primary Examiner.

DAVID J. w1LLIAMowsKY,Examiner. 

1. IN COMBINATION WITH A SEWING MACHINE INCLUDING A SEWING NEEDLE AND MEANS FOR ADVANCING A WORK PIECE ALONG A PREDETERMINED PATH PAST SAID SEWING NEEDLE, A PIVOTALLY MOUNTED ARM SWINGABLE BETWEEN A RAISED AND A DEPRESSED POSITION AND MEANS NORMALLY URGING SAID ARM TO SAID RAISED POSITION, AN ELECTRICALLY HEATED HOT WIRE CUTTING ELEMENT MOUNTED ON AND EXTENDING BEYOND SAID ARM AND SWINGABLE WITH SAID ARM BETWEEN A RAISED AND A DEPRESSED POSITION ACROSS SAID WORK PIECE PATH FORWARD OF SAID NEEDLE, AND A PIVOTALLY MOUNTED ACTUATING MEMBER INCLUDING A CAM SURFACE ALONG ITS UPPER EDGE DISPOSED ALONG THE PATH OF SAID WORK PIECE AND MOVABLE WITH SAID ACTUATING MEMBER BETWEEN A RAISED AND A DEPRESSED POSITION, SAID ACTUATING MEMBER FURTHER INCLUDING AN UNDERSURFACE REGISTERING WITH THE UPPER SURFACE OF SAID ARM WHEREBY SAID ACTUATING MEMBER IS NORMALLY HELD IN ITS RAISED POSITION BY SAID ARM AND SAID URGING MEANS AND MOVABLE TO SAID DEPRESSED POSITION WHEN SAID CAM SURFACE IS DEPRESSED BY ENGAGEMENT WITH A WORK PIECE PASSING THEREOVE TO THEREBY EFFECT A MOVEMENT OF SAID ARM AND SAID CUTTING ELEMENT BETWEEN SAID RAISED AND DEPRESSED POSITIONS IN RESPONSE TO THE RESPECTIVE RAISING AND DEPRESSION OF SAID ACTUATING MEMBER TO THEREBY CUT THREADS POSTIONED IN THE PATH OF SAID CUTTING ELEMENT ON EITHER THE UPSTROKE OR DOWNSTROKE OF SAID CUTTING ELEMENT. 